Device having a voltage-controlled oscillator and a switching arrangement for self-calibration
A device, particularly a radar sensor, has a voltage-controlled oscillator for generating a high-frequency signal which has an actual frequency, a voltage adjusting device to control the oscillator, and a calibration device operable for adjusting a voltage value which is assigned to a value of a target frequency. The calibration device is operable for finding a difference between a frequency and the target frequency corresponding to the voltage set at the oscillator. The calibration device is also operable for generating a low-frequency signal from the high-frequency signal, determining the oscillation period of the low-frequency signal, calculating an auxiliary frequency from the oscillation period of the low-frequency signal, wherein the auxiliary frequency corresponds to the actual frequency of the high-frequency signal, and for adjusting the voltage value assigned to the target frequency according to the frequency difference between the auxiliary frequency and the target frequency.
1. A radar sensor, the radar sensor comprising:
a millimeter monolithic integrated circuit comprising:
a voltage-controlled oscillator for generating a high-frequency analog signal which has an actual frequency,
a first frequency divider in communication with the voltage-controlled oscillator and the analog to digital converter for generating a first low-frequency digital signal from the high-frequency analog signal generated by the voltage-controlled oscillator,
an analog to digital converter within the millimeter monolithic integrated circuit or in direct communication with the millimeter monolithic integrated circuit, and
a digital signal processor in direct communication with the millimeter monolithic integrated circuit, the digital signal processor including:
a second frequency divider for generating a second low-frequency digital signal having a frequency less than the first low-frequency signal,
a counter in direct communication with the second frequency divider for determining an oscillation period of the second low-frequency signal,
a processor in direct communication with the counter for calculating an auxiliary frequency of the second low-frequency signal from the oscillation period,
said processor also finding a frequency difference between the auxiliary frequency and a target frequency,
a calibration device in direct communication with the processor to adjust the voltage value which is assigned to a value of the target frequency according to the frequency difference between the auxiliary frequency and a target frequency, and
a voltage adjusting device in direct communication with the calibration device for adjusting a digital voltage value of the oscillator, and
a digital to analog converter for converting the digital voltage value to an analog voltage value and providing the analog voltage value to the voltage-controlled oscillator.
2. The radar sensor according to claim 1 , characterized in that one of the frequency dividers is integrated into an integrated phase lock loop.
3. A method for the control of a radar sensor, the steps comprising:
generating a high-frequency analog signal which has an actual frequency via a voltage-controlled oscillator,
generating a first low-frequency digital signal from the high-frequency analog signal generated by the voltage-controlled oscillator via a first frequency divider and an analog to digital converter,
generating a second low-frequency digital signal having a frequency less than the first low-frequency signal via a second frequency divider,
determining an oscillation period of the second low-frequency signal via a counter in direct communication with the second frequency divider,
calculating an auxiliary frequency of the second low-frequency signal from the oscillation period via a processor in direct communication with the counter,
finding a frequency difference between the auxiliary frequency and a target frequency via said processor,
utilizing a calibration device in direct communication with the processor to adjust the voltage value which is assigned to a value of the target frequency according to the frequency difference between the auxiliary frequency and a target frequency,
utilizing a voltage adjusting device in direct communication with the calibration device for adjusting a digital voltage value of the oscillator, and
converting the digital voltage value to an analog voltage value using a digital to analog converter and providing the analog voltage value to the voltage-controlled oscillator.
4. The method according to claim 3 , wherein the adjustment of one of the voltage values is directly calculated from the frequency difference, while the adjustments of further voltage values are determined by at least one of interpolation and extrapolation.